Struvite-K and Syngenite Composition for Use in Building Materials

ABSTRACT

A composition and process for manufacture thereof used in hybrid inventive building materials comprising Syngenite (K2Ca(SO4)2.H2O) and Struvite-K (KMgPO4.6H2O). Starting constituents include magnesium oxide (MgO), monopotassium phosphate (MKP) and stucco (calcium sulfate hemihydrate), mixed in predetermined ratios, cause reactions to proceed through multiple phases, which reactions variously are proceeding simultaneously and in parallel. Variables, e.g., water temperature, pH, mixing times and rates, have been found to affect resultant reaction products. Preferred ratios of chemical constituents and manufacturing parameters, including predetermined weight percent and specified ratios of Struvite-K and Syngenite are provided for building products used for specified purposes. Reactions are optimized in stoichiometry and additives to reduce the combined heat of formation to non-destructive levels. Various additives help control and guide reactions. Building products, such as board panels, include the resultant composition. A significant amount of the composition is disposed adjacent a building panel face.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a non-provisional application relying for priority on U.S.patent application Ser. No. 14/457,826 filed on Aug. 12, 2014, on U.S.Provisional Application No. 61/890,702, filed on Oct. 14, 2013; on U.S.Provisional Application No. 61/890,720, filed on Oct. 14, 2013, U.S.Provisional Application No. 61/892,025, filed on Oct. 17, 2013, on U.S.Provisional Application No. 61/892,581, filed on Oct. 18, 2013, and onU.S. Provisional Application No. 61/915,601, filed on Dec. 13, 2013, theentire specifications of which are incorporated by reference as if fullyset forth herein.

BACKGROUND OF THE INVENTION 1. Field of the Invention

This invention relates generally to building materials and morespecifically to building materials in which a desired final compositionand ratio of Struvite-K and Syngenite, two minerals not normally foundtogether, is provided to impart specified and predetermined propertiesand characteristics to the building materials.

2. Background Art

For approximately three thousand years, and at least since Roman times,magnesium oxide (MgO) based cements have been used to build walls andstructures. Within the last 50 years, improved magnesium oxidecontaining materials have been used for batch manufacture of slurriesthat are then poured into panel molds where they are allowed to cure foran extended period of time. The resulting products impart rigidity andstructural integrity to the panel and thereby allow the panel to befastened to wall assemblies.

Wallboard typically has a density range of from about 1,600 pounds(lbs.) to about 1,800 lbs. per thousand square feet (lbs/MSF) (about 7.8kilograms (kg) to about 8.3 kg per square meters (m²)) of about one-halfinch (1.27 cm) board. Heavy or high-density gypsum wallboards are costlyand more difficult to manufacture, transport, store, and manuallyinstall at job sites. The recent trend has been toward lighter orlow-density boards. While wallboards having reduced densities throughadding lightweight fillers and foams are known, wallboard having adensity of less than about 1,600 lbs/MSF (about 7.8 kg per m²) in aone-half inch (1.27 cm) board, may reduce the strength and integrity ofthe resulting board. Because extra high-density or heavy gypsumwallboard generally is not desirable for the reasons set forth above,research and development are proceeding apace in order to producereduced weight or density boards without sacrificing board integrity andstrength. One method of reduction of board weight is to use novel ornon-gypsum materials for the core of the boards.

Struvite [(NaH₄(PO₄).6(H₂O)] has been known as a naturally occurringmineral for over a century, and has been the subject of study in thehealth process of animals and sewage treatment. See, for example, USPublished Patent Appl. No. 2013/0062289, among others. A more recentdevelopment has resulted in a similar, albeit artificially created,mineral, alternatively known as K-Struvite, Struvite-K or Struvite (K)(hereinafter “StruviteK”), having the chemical formula[KMg(PO₄).6(H₂O)]. This essentially man-made mineral has been thesubject of intense study because many of its salient characteristics,including its orthorhombic crystal structure, glassy sheen, whichpermits substantially friction free motion, and resistance to heattransfer, have been found very suitable in the building industry.

Because of these and other properties, and from the desire in thebuilding and construction industries to find a feasible alternative togypsum boards as internal building materials, Struvite-K has beendetermined to provide a good heat resistant building board panel whileremaining slightly elastic and providing ease of manufacture on a massscale comparable to that of gypsum board.

It is well known that such magnesium oxychloride containing panels aremore expensive, usually amounting to twice to three times the cost oftraditional gypsum building panel alternatives, see for example, US PatPub. Nos. 2013/0115838 published on May 9, 2013. Therefore, these typesof boards are not widely accepted as cost affordable building materialsfor wall boards or panels. Moreover, some magnesium oxychloridecontaining building panels produce free chlorine gas within the boardmaterial, and thus present major issues, such as leaching, foul odors,fastener and building structure corrosion. In addition, many of thesetypes of boards will breakdown and decompose over time, as they are notchemically stable. These types of boards and panels are particularlysusceptible to long term water exposure, and are prone to fall apartunder long exposures to such conditions.

In recent years, environmental and health safety driven building codeshave mandated that only building materials capable of offering improvedwater resistance and or fire resistance can be used in certainconstruction structures and building methods. As a result, paperlessgypsum and traditional cement building panels have evolved to satisfythese requirements. However, gypsum is not and cannot ever be waterproof and or completely water resistant. Therefore, it is necessary thatwater resistant compounds, such as waxes or silicones, be added to theirformulation to impart acceptable water resistance. This may be a costlyand perhaps unnecessary addition.

Moreover, the traditional fiber cement and Portland cement buildingpanels are extremely difficult to handle and work with when used intraditional building practices, and thus require more time, labor andspecialized tools to prepare and install these types of building panels.

More recently, the international economic situation has affected thebuilding and construction markets. Consequently, construction companieshave been driven to seeking alternative building materials that offerimproved performance characteristics that are at least an order ofmagnitude greater than those of traditional gypsum and cement buildingmaterials, while simultaneously matching the cost effectiveness ofgypsum and cement building materials.

This invention addresses the simultaneous tension between cost andeffectiveness, while providing for a method of using a continuous boardline. The dual considerations of functional effectiveness and reductionof costs, in the context of improved and engineered building materialsdesigned to serve specific purposes, would provide an ideal buildingmaterial if all the considerations are adjusted to obtain such boards orpanels. None of the heretofore disclosed known prior art building boardcompositions can provide these capabilities. None of the prior artmethods known heretofore teach the inventive process of formingcomposite boards containing synthetic Struvite-K and Syngenite inspecified ratios so as to provide desired characteristics and featureson wall board panels, utilizable to provide an ultra-lightweight boardor building panel, that is moisture and fire resistant.

SUMMARY OF THE INVENTION

Accordingly, there is provided herein a new and improved composition andprocess for the production of a novel building material, comprising asstarting constituent compounds magnesium oxide (MgO), monopotassiumphosphate (MKP) and calcium sulphate including stucco (calcium sulfatehemihydrate). The reaction products, Syngenite (K₂Ca(SO₄)₂.H₂O) andStruvite-K (KMgPO₄.6H₂O) proceed through multi phase reactions, at timesoccurring simultaneously. The reactions are basic in the case of thehemihydrate and water and acidic for the Magnesium Oxide/MKP, bothreactions taking place simultaneously and in parallel and may evencompete with each other if the Struvite-K reaction is not buffered (rateslowed down) to allow the hemihydrate enough time and water to fullyrehydrate. It is considered that the Syngenite reaction (typically anexothermic reaction) will reach a maximum temperature of 109-186° F.(42°−86° C.),—depending on the purity of the hemihydrate, and itsconcentration). In this case the first co-reacting temperature rise isan endothermic reaction and the formation of Syngenite is taking placeas a product of dissolution from the MKP-K, which is liberated from theMKP and together with the forming hemihydrate forms K₂Ca(SO₄)₂.H₂O(Syngenite) before the Struvite-K nears its own initial temp rise (anexothermic reaction—temperatures can hit a maximum of 212 F.° (100° C.)with some reactions observed to exceed these temperatures). Thistemperature rise, if left unchecked, may pose a major destructive effectto the hemihydrate portion of the formed Syngenite, even after itbecomes fully rehydrated. The invention disclosed and claimed herein isa preferred set of ratios of chemical constituents and a method ofmanufacture of board panels using a continuous line includingpredetermined and specified ratios of Struvite-K and Syngenite forspecified purposes, optimized in respect of stoichiometry to reduce thecombined heat of formation to non-destructive levels and additionally, amethod of manufacture of board panels utilizable in buildingconstruction that is fire and moisture resistant, as well as a varietyof board products made according to these methods and using theinventive materials.

In one sample, the core mechanism has stoichiometric amounts of MgO andKH₂PO₄ in the presence of water and hemihydrate stucco to obtainStruvite-K and Syngenite and other amorphous by-products. This mechanismis considered to follow the reaction:

MgO+KH₂PO₄+CaSO₄.½H₂O→KMgPO₄.6H₂O+K₂Ca(SO₄)₂.H₂O.

In another embodiment, together with the initial constituents and traceadditives, the reaction may comprise several subreactions, but theoverall general reaction follows the mechanism:

3MgO+3KH₂PO₄+2CaSO₄.½H₂O+3H₂O→KMgPO₄.6H₂O+K₂Ca(SO₄)₂.H₂O+Ca⁺²+2Mg⁺²+2(PO₄)³

in the presence of Boric Acid (H₃BO₃), Naphthalene Sulfonate, SulfuricAcid (H₂SO₄) and a siloxane, such as polydimethylsiloxane or poly(methylhydrogen) siloxane. It should be noted that the above reaction is notyet considered to complete total reaction product mixtures, and thestucco hemihydrate (CaSO₄.½H₂O) will remain in excess. It is consideredthat the remaining ionic materials, i.e., (Ca⁺², 2Mg⁺² and 2(PO₄)⁻³)will either react with the remaining stucco or will form saltagglomerations upon drying. It is considered that at least some of thestucco hemihydrate and the Magnesium Oxide remain unreacted, and theseconstituents remain in an amorphous, randomly distributed matrix withinthe crystalline structures that are presented by the reacted Struvite-Kand Syngenite, as shown in FIG. 1.

It should further be noted that the constituent materials may beprovided in varying predetermined ratios, and may be included inspecified ratios for the main constituents MgO:MKP as a 1:1 ratio up toa ratio of 1:3.4. Thus, although the constituent materials identifiedabove and the resultant reactant products are shown as having specifiedratios, it should be understood that varying the initial constituentratios, as has been done in trials described below, changes the reactionproducts and the amounts of reacted and unreacted constituents.Specified weight percent ranges are provided for in the followingproportions:

MgO: 3.33 to 70.00%

KH₂PO₄: 4.67 to 70.00%CaSO₄.½H₂O: 10.5 to 90.0% adding up to 100%.

In a more refined ratio of the constituent starting materials, thefollowing proportions are preferred:

MgO: 10.0 to 40.0%

KH₂PO₄: 40.0 to 70.00%CaSO₄.½H₂O: 25.0 to 75.0% adding up to 100%.

To both of these solid constituent mixtures, water is added to commencethe reaction in the proportion in a range of from 100:20 up to 100:40weight percent of solid constituents to water. In a preferred form ofthe reaction, it is carried out in a reaction mixer in a continuousprocess, and the resulting slurry comprising mostly Struvite-K,Syngenite, gypsum, and some potentially unreacted constituents providesa semi-liquid paste that is used in association with or without a gypsumcore to provide one or more gypsum board products. In an optimalformulation, the ratio of MgO:MKP is from between 1:1.8 to 1:2.2, and ina most optimal formulation most closely most approximates 1:2.0.

In another embodiment, there is disclosed and claimed herein empiricallyderived ratios of constituent materials and guidelines for defining theprocess parameters in the manufacturing process of building materialscontaining unique building compositions including the mineralsStruvite-K and Syngenite. These preferred ratios define the reactantcomposition of magnesium oxide (MgO), a phosphate and a potassiumcontaining reactant, such as monopotassium phosphate (KH₂PO₄), andhemihydrate alpha and/or beta gypsum (CaSO₄.½H₂O), in solution withwater (H₂O), together with judicious use of thermodynamic and kineticproperties of these chemical reactions, to guide the reactions in thedesired direction and thereby to obtain the unique building materialshaving the desired physical properties.

The mathematical ratios utilize thermodynamic and stoichiometricprinciples and are grounded in the laws of conservation of atomiccomposition, energy and mass. The mathematical ratios use a desiredcomposition in the final product building materials containingStruvite-K and Syngenite and provide the following process parameters towithin an accuracy of 5% of the actual process conditions:

-   1. Thermodynamic quantities of the process, including but not    limited to the Gibb's free energy of formation, the enthalpy of    formation, and the entropy of formation;-   2. Rheology of the mixture, including but not limited to the density    and viscosity;-   3. Reactant masses and/or ratios of magnesium oxide (MgO),    monopotassium phosphate (KH₂PO₄), stucco, in the form of Hemihydrate    Alpha and or Beta gypsum (CaSO₄.½H₂O) and water (H₂O);-   4. Process conditions, including but not limited to temperatures and    pressures of reaction, water content, mixing rate, mixing time, and    pH.

Using appropriate mathematical equations, a user may determine a greatvariety of possible formulas and process iterations toward providingunique building materials containing Struvite-K (KMg(PO₄).6(H₂O)) andSyngenite (K₂Ca(SO₄)₂.H₂O), all in accordance with the disclosure of thechemical reactions disclosed in aforementioned copending U.S. patentapplication Ser. No. 14/457,826, and U.S. Provisional Application Nos.61/865,029 and 61/892,581. Use of the processes and innovative methodsdescribed herein can provide cost efficient, ultra low weight wallboardshaving enhanced performance capabilities, such as mechanical strength,fire and moisture resistance and anti-microbial properties.

Certain qualitative trends can be seen from preliminary lab results andscientific deductive reasoning using known scientific principles. Theabove listed 5 process conditions may be used to predict the necessarystarting conditions based on the yields of Struvite-K and Syngenitedesired in the final mixture. The possible modifications of the initialparameters will now be described in greater detail to show the effect ofhow varying any one particular parameter will change the ultimateresulting composition derived from the starting constituents.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be discussed in further detail below withreference to the accompanying figures in which:

FIG. 1 is photomicrograph of a void in the resulting material developedin one of the tested formulations to determine the local structure ofthe resultant reaction products;

FIG. 2 is a ternary graph showing the proportions of MgO:MKP:stucco forspecified trial runs and plots the various formulations used in thetesting regime; and

FIG. 3 is a schematic plan view showing in cross-section a plug flowmixer reactor such as may be utilized in the production of the inventivecompositions of matter.

FIG. 4 is a side view showing in a schematic the chemical constituentsthat are loaded into a mixer to facilitate the mixture of elements toproduce the inventive composite material.

FIG. 5 is a side view in several sections schematically showing a boardproduction line such as may be utilized in the production of theinventive board panels.

FIG. 6 is a cross-sectional side view of one embodiment of an inventiveboard panel.

FIG. 7 is a cross-sectional side view of another embodiment of aninventive board panel.

FIG. 8 is a cross-sectional side view of yet another embodiment of aninventive board panel.

FIG. 9 is a cross-sectional side view of still another embodiment of aninventive board panel.

FIG. 10 is a cross-sectional side view of another embodiment of aninventive board panel.

FIG. 11 is a cross-sectional side view of yet still another embodimentof an inventive board panel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The inventive chemistry is set forth in the aforementioned patentapplications, and is repeated below. To be avoided in the reaction isthe overwhelming heat that the Magnesium Phosphate reaction generatesexothermically which inhibits the simultaneously occurring stuccorehydration reaction and avoids generation of excessive amounts ofamorphous gypsum hemihydrate as an unwanted by-product. Thus, to providean appropriate buffer is considered essential. Boric acid is ideal toretard the Magnesium Phosphate reaction, while it also serves as amechanism to protect gypsum recrystallization against the adverseeffects of thermal shock when the Magnesium Phosphate begins to form.

Use of sulphuric acid (H₂SO₄) to pre-treat the water provides a moreacidic solvent and thus further accelerates the Struvite-K reaction. Toreduce costs of materials, use is made of stucco, inducing as much as90% by weight of the overall formulation, as a replacement co-reactant.The stucco replaces predetermined amounts of Magnesium Oxide andmonopotassium phosphate (MKP), which significantly reduces cost, sincethe gypsum stucco is cheaper and lighter weight than these materials.

As a by-product and a point of unexpected discovery, another importantmineral, Syngenite, is also generated in the stucco reaction. Syngeniteis more fire resistant than gypsum. However, Syngenite by itself is notas strong and fire resistant as the combination of Struvite-K andSyngenite. Syngenite also provides an incidental benefit as acompositing factor between the Magnesium Phosphate and the gypsumhemihydrate, whereby it incorporates plasto-elastomeric characteristics,thereby rendering the final product significantly less brittle and moreflexible, increasing manipulability, and making the board easier toscore/cut. This is a significant improvement over known Magnesium“Oxychloride” boards, for example, such as those described in U.S. Pat.Pub. 2013/0115835 and Portland cement based cement building panels.

Additionally and ideally, silicone is added to the mix to achieve fourother complementary benefits,

-   1) forming a catalyzed silicone in the presence of the Magnesium    Phosphate and acids-   2) providing a mechanism for thermal resistance to the gypsum and    permits recrystallization of the Magnesium Phosphate-   3) serving to retard the Magnesium Phosphate reaction, and-   4) providing a defoaming material to break down any foam that may be    generated as a byproduct of the reaction of the Sulfuric Acid with    CaCO₃, which is a known impurity in natural gypsum. Increasing the    amount of silicone addition further imparts substantial water    resistance to the board, and in increase in catalyzed silicone even    more so. Total water resistance has been increased using    significantly a lesser amount of silicone than is typically    used/required to meet ASTM performance requirements for wet area    building panels. Testing has shown that a maximum absorption rate of    <2% may be achieved, while typically results on conventional water    resistant gypsum wallboard, glass-reinforced gypsum boards, produce    on average absorption that is at best 3.5% to 4% total water    resistance.

However, the materials generated as a result of the present inventionare by their nature water resistant and do not breakdown in the presenceof water as would, for example, Magnesium Oxychloride boards ortraditional gypsum boards, which require the incorporation of waterresistant additives, such as wax or silicone. Incorporation of aPolysiloxane in the present formulations restrains water wicking intothe open areas and through the matrix of the products made in accordancewith the present invention, essentially making it water impervious to anextent that water is no longer able to wick into the material. Moreover,even when bulk water or vapor water either wicks into or is transferredinto the material/materials generated according to the presentinvention, it has no detrimental effect thereon and the materialmaintains its original strength. So as to prevent the intrusion of bulkor vapor water into and throughout the inventive compositions, aPolysiloxane is added only if complete water imperviousness is arequirement, for example, such as in regions and localities wherebuilding codes have driven the specification.

One method of using Struvite-K in building materials has been suggestedfor use in roads in replacement of Portland Cement. See for example:“Optimisation of the preparation of a phosphomagnesium cement based onstruvite and K-struvite” H. Hammi and A. Mnif, Laboratoire deValorisation des Matériaux Utiles, Centre National de Recherches enSciences des Matériaux, Technopole Borj Cedria, Soliman, Tunisie, MATECWeb of Conferences Vol. 3, page 01071 (2013). Such compounds have alsobeen found to be useful in the production of other building materials,such as wallboard panels, ceiling tiles, etc. Such uses require theefficient, timely and inexpensive production such that they can beincorporated into the structural members in which they are being used.

It has been noted that the production of such compounds and theirability to set in a timely fashion is dependent on the stoichiometry ofthe various precursors to the final set product, which is essentially inthe form of KMg(PO₄).6(H₂O). That is, it has been found as a surprisingand unexpected result that the ratios of ingredients as follows willprovide the best results in the desired characteristics:

The following scientific principles are implement to assist in drivingthe rapidity and direction of the reactions:

1. Thermodynamic principles:

-   a. The Gibb's free energy of formation, the enthalpy of formation,    and the entropy of formation all indicate the dominance of the    Struvite-K and Syngenite reactions

2. Rheology of the reaction mixture:

-   a. The density and viscosity of the mixture increase as higher    Struvite-K yields are produced.

3. Reactant masses and stoichiometric considerations:

-   a. The ratio of MKP:MgO will increase as higher Struvite-K yields    are produced until the ratio of MKP:MgO reaches, but does not    exceed, 3.37:1.-   b. Stucco (gypsum hemihydrate)—the stucco requirement will not be    affected by variation of other elements providing for higher    Struvite-K yields, as stucco does not take part in this reaction.-   c. Water—the water requirement will increase as higher Struvite-K    yields are produced until the mass ratio of monopotassium phosphate    (KH₂PO₄) to water (H₂O) equals 2.96:1, from stoichiometric    considerations.

4. Process Reaction Conditions:

Water content, mixing rate, mixing time, pH, and temperature of thewater are all considered as significant factors in the resultantproducts and by-products.

The chemical reaction providing the optimum results has been determinedto be:

the reaction occurring in the presence of small amounts of H₂SO₄, H₃BO₃,acting to control the reaction rate, and including one or more siloxanesto restrain water wicking. Although lingosulfaonate or corboxylate formsare usable, Naphthalene Sulfonate is preferred as a fluidizer.

The Struvite-K Reaction is an exothermic reaction and proceeds veryrapidly. The basic core reaction is represented by:

MgO+KH₂PO₄+5H₂O→KMg(PO₄).6(H₂O).

The Syngenite Reaction is broken up into two separate subtractions, thebasic mechanism being represented by:

2CaSO₄.½H₂O→H⁺+½O²⁻+2Ca²⁺+2SO₄ ²⁻ and

Ca²⁺+2SO₄ ²⁻+2K⁺+H₂O→K₂Ca(SO₄)₂.H₂O+CaSO₄.

The precise reaction mechanism remains under study, and that certainreaction parameters, such as pH, water temperature, and timing of mixingand additions, have been explored as set froth above. The initialprocess parameters are considered to affect the reaction rates, productsand final structures. Continued study and data derived therefrom isexpected to provide a basis that will enable customization of thereaction products and extent of completion of the reaction, as may bedesired for specific applications.

In the current invention, it has been found that the degree and lengthof mixing plays a significant role, but as a secondary order ofmagnitude. Both how the reaction proceeds and the ultimate yield ofSyngenite and Struvite-K are considered to be affected. Using the ratiosas provided above, it has been found that minimal mixing yields higherratios of Syngenite and longer mixing yields higher ratios ofStruvite-K. Unexpectedly, it was discovered that a short mixing periodenables a first, low temperature generating exothermic reaction and,when the mixing is stopped minimally after 30 seconds to one minute,complete set/hardening of the slurry can take up to 50 minutes. X-RayDiffraction (XRD) tests have indicated that samples mixed this way yieldhigher amounts of Syngenite than Struvite-K, as well as elevated ratiosof unreacted MgO (Periclase has been observed) and Bassanite(CaSO₄.½H₂O). Though each sample appeared to be set after this shortmixing, in fact it was unexpectedly discovered that the sample had onlyformed a shell around an unset—still fluid—inner core, and that thesample maintained a temperature around 86° F. (30° C.). The shell wasbroken open and all materials were found to go back into solutionimmediately when mixed with the still fluid inner core material. Furthermixing for an additional 30 to 40 seconds instigated a secondreaction—an exothermic reaction wherein the temperature was observed toclimb to a maximum of 212° F. (100° C.), initially thought to beindicative of a magnesium phosphate reaction. However, following an XRDtest on this sample material, it was determined to comprise Struvite-K.

Subsequent prolonged multi and single stage hand mixing and high speedmixing of follow-up samples composed/formulated with an identicalformulation as listed below, demonstrated dramatically elevatedStruvite-K yield ratios.

XRD results demonstrate the benefit of prolonged mixing of the 1:2:1MgO:MKP:Stucco and resulting ratios are set forth below. Table 1 showsthe mixing process of the same constituent materials and ratios(MgO:MKP:Stucco) to show repeatability of the reaction rate products.

TABLE 1 KMgPO₄•6H₂O K₂Ca(SO₄)₂•H₂O Unreacted MgO CaSO₄•0.67H₂O(Struvite-K) (Syngenite) (Periclase) (Bassanite) (PDF-00-035-(PDF-00-028- (PDF-00-045- (PDF-00-047- Samples 0812) 0739) 0946) 0964) A67.1 25.0 6.6 1.2 B 66.4 25.8 7.1 0.7 C 66.0 26.4 6.9 0.6 D 66.0 26.46.9 0.6

Mixing as described above in combination with the specific formulationshown above and raw material addition variations detailed below resultin the novel and unexpected discovery, distinguishing previously knownmagnesium oxide or magnesium oxychloride type boards.

Combining the formulation above with suitable changes to the followingranges imparts improved economic efficiencies relating to large scaleStruvite-K yield as a result of the process/formulation.

For generating more Struvite-K than Syngenite, the following method isused:

-   a. Using a multi-stage mixing apparatus, such as a plug flow mixer    as shown in FIG. 3, multilevel pen or scraper mixer, or combination    thereof, or alternatively using only a mixer that allows for a long    dwell time with raw material supply and feed-through/output to    control equivalent to a manufacturing speed for a typical 4 foot    wide and ¼ to 1″ thick board ranging from approximately a minimum of    20 feet/min to a maximum of 750 feet/min, the raw materials are    mixed and combined within the mixer as follows: (Dwell time must be    equal to or greater than and min of 4 minutes and a max of 12    minutes). Less than 17.2% Magnesium Oxide (MgO) from one or more    appropriate sources, such as light dead burned, medium dead burned,    hard dead burned MgO, are intended to optimize and reduce raw    material cost meanwhile yielding both efficient and optimal    performance features in the result composite generated slurry    formulation.-    A greater amount of Mono-Potassium Phosphate (MKP) or alternatively    Potassium Dihydrogen Phosphate—KH₂PO₄ (KDP) of at least 34.5% will    increase the molar ratio of Magnesium Oxide (MgO) to potassium    Dihydrogen phosphate and also will cause a reduction in the rate of    reaction via reduced rate of dissociation. The preferred MKP or KDP    may be either of food grade or agricultural grade.-    At least 17.2% Beta Hemihydrate Stucco, that is, processed    stucco—CaSO₄.½H₂O) added as a co-reactant which generates an initial    reaction with the MKP or DKP. This reaction slows the continuing    co-reaction (Ca²⁺+2SO₄ ²⁻+2K⁺+H₂O→K₂Ca(SO₄)₂.H₂O+CaSO₄) via an    initial rehydration/uptake of associated water. This initial step    generates a first temperature rise from the exothermic reaction, to    counter the endothermic reaction with the potassium (setting off a    dissolution of the K from the MKP to join with the forming dihydrate    to form Syngenite). The Hemihydrate stucco may have a purity range    of from minimum of approximately 65% to a maximum of 100%. Higher    purity hemihydrate stucco improves the uptake of potassium as    dihydrate is forming and thereby further slows the secondary    KMgPO₄.6H₂O (Struvite-K) reaction thus increasing the yield of    Struvite-K in the final reaction. Because the exothermic reaction    that generates the KMgPO₄.6H₂O is hot (up to 212° F. (100° C.) and    sometimes above), the rehydrated dihydrate portion of the derived    Syngenite calcines to a minor extent. The Potassium (K) that had    been used up in the first Syngenite reaction is then released into    solution in stages and is ultimately reused in the KMg₂PO₄.6H₂O    generation process as the continuous reaction proceeds.-    About 31.1% H₂O (Water) is introduced as a solute to permit the    other reactions to proceed.-    Trace remaining additives are preferably introduced to assist the    reactions. These all represent less than 1.5% of the overall dry mix    in total combined addition.

a. Sulfuric Acid (H₂SO₄): is added to the water to change the pH andimprove the instigation of the overall acid based reaction.

b. Boric Acid (H₃BO₃): Boric Acid is an important additive because itoffers a benefit to both endothermic and exothermic reactions. In thefirst reaction, it serves to protect the hemihydrate to waterrehydration from the heat of the secondary MgO/MKP/H₂O reaction, andallows the forming Syngenite to retain association with the Potassiumfor a longer period. In the case of the MgO/MKP/H₂O reaction, the BoricAcid is a known retarder generally to Magnesium Phosphate Cementreactions, delaying this reaction to reduce thermal shock.

c. Siloxanes, such as Polysiloxane (C₂H₆OSi)_(n), polydimethylsiloxane(CH₃[Si(CH₃)₂O]_(n)Si(CH₃)₃), and similar compounds, in very lowaddition amounts, are provided as a defoamer. The MgO/MKP and anyimpurity within the Hemihydrate source (CaCO₃) reacts with the MgO inthe presence of water to cause a foaming reaction that is not desirable.If no impurities are present, the Polysiloxane stays intact throughoutthe entire course of the first and second reactions, and is utilized asneeded for a continuous feed.

d. Naphthalene Sulfonate, such as C₁₀H₈NNaO₃S, in very low additiveamounts serves as a fluidizer or dispersant for the overall mix.

The purity of Beta Hemihydrate stucco is an additional factor, sincehigher purity hemihydrate causes the overall reaction to slowdown/retard and permits a greater uptake of K, again skewing the initialreaction toward more generation of Struvite-K in the final reaction. Theadditives in their current disclosed addition ratios should beapproximately maintained. Nevertheless, a maximum Struvite-K yield limitis reached. It is noted that decrease of either MgO or MKP additionswill yield less Struvite-K. Increase in MgO and or MKP additives shouldgenerate equivalent or greater yield ratios of Struvite-K, but to do sorequires an increase in the Beta hemihydrate stucco addition or anincrease in the hemihydrate stucco purity. In this case the Boric andSulfuric Acid additions may also be increased to compensate.

The above described process changes the ratios somewhat so thatcombining the formulations that above with the following ranges willimpart improved economic efficiencies relating to large scale Syngeniteyield as a result of the process/formulation. In order to generate moreSyngenite, the method uses a multi-stage mixing apparatus such as a plugflow mixer, multilevel pin and or scraper mixer or combination andsources of materials are as above. However, changes to the inputparameters of the constituent materials skew the reactions toward adifferent yield result.

Magnesium Oxide (MgO) is provided in amounts greater than 17.2%: MKP orKDP is less than 34.5% and Beta Hemihydrate stucco (CaSO₄.½H₂O) is inputin amounts greater than 17.2%, with H₂O (Water) remaining at a nominalvalue of 31.1 weight percent of the solid constituents. The remainingadditives representing less than 1.5% of the overall mix in totalcombined addition remain essentially the same. However, it is understoodthat the changes in the ratios between the MgO, MKP and CaSO₄.½H₂O toachieve desired yields requires appropriate stoichiometrical changes ofthe three constituents.

To generate equivalencies of both Syngenite and Struvite-K—the reactionsmust be balanced in a way to enable the second exothermic reaction toexist within the 180° F. to 212° F. (82.2-100° C.) temperature range,but reducing the temperature rise from and time of the exothermicreaction will also reduce the ratio of Struvite-K yield. It has beenfound that the mixture as set forth above provides a significantlygreater yield of the Struvite-K, up to 67%, than heretofore provided byknown processes, with a minimum of additional necessary inputs or costlyprocess steps or additives.

In the end, the gypsum component makes the inventive board panel moreaffordable to a variety of consumers. The final board panel productprovides for a dramatic improvement both in physical characteristics andin long-term performance over conventional gypsum panels. The productsare naturally UV resistant, that is, the are capable of protectingagainst penetration of ultraviolet rays, so no need exists forperformance surface coatings. The products are extremely waterresistant. A similar product was described by Surace in GB 2,445,660,equivalent to U.S. Pat. Pub. No. 2008/171,179. While the described boardwas capable of being produced in a continuous and/or batch process,Surace clearly teaches that the use of hemihydrate gypsum stucco is tobe avoided because of the requirement of significant energy input neededto dry the hemihydrate. In the above described product, simultaneousproduction of Syngenite causes a stoichiometric reaction that requiresno added external heat for drying, the exothermic reaction therebyproviding the necessary thermal energy for the endothermic reaction.That is, the reaction of the hemihydrate with the monopotassiumphosphate (MKP) provides the heat of reaction utilized for driving thesecond reaction, as above.

In use, boards having the specified compositions of Struvite-K inspecified ratios to the Syngenite can be tailored for specific desireduses. An initial attempt to provide a light weight board panel includedthe following steps to obtain a sample result:

The initial base material formulation was a 1:1:1 mixture, that is,comprising in equal proportions MgO:MKP-(KH₂PO₄):stucco (hemihydrateCaSO₄.½H₂O), with the MgO, MKP and hemihydrate gypsum being added indoses of 15 g each as dry powder to the mixer and dry premixed for 45seconds to ensure homogeneity of the materials. Other, and for the mainreaction, optional, material additions were 0.03 g silicone oil, such aspolymethylhydrogensiloxane, and a dispersant, comprising 0.05 gpolynapthalene sulfonate.

To this base mixture, following the dry mix for all samples below, 17 gwater (H₂O) was added. This base mixture was then used for several labruns, by the additions of varying materials for testing purposes, asnoted in the table below, and several samples as listed in TABLE 2 weretested. The mixture, including the water, was mixed in a mixer (by hand)for a period of about 30 to 60 seconds in a first phase, and thenallowed to partially set and then mixing was again begun on the productwhich had partially set around the outside in a shell structure, leavinga central core still in a liquid state. When the mixing was begun in thesecond phase, the set outer shell immediately went back into solution,and after mixing again for about 30 to 45 seconds, the material wasallowed to set completely.

TABLE 2 Sample Utilizing the above Base formulation the No. followingmaterials were added by weight 1 boric acid (H₃BO₃) 1 g 2 H₂SO₄ 0.05 g 3H₂SO₄ 0.05 g + boric acid (H₃BO₃) 0.25 g 4 H₂SO₄ 0.05 g + (H₃BO₃) boricacid 0.50 g 5 H₂SO₄ 0.05 g + boric acid (H₃BO₃) 0.25 g + an extra 2.25 gH₂O 6 H₂SO₄ 0.05 g + boric acid (H₃BO₃) 0.25 g + extra 7.5 g KH₂PO₄(1.5x of base form.) 7 H₂SO₄ 0.05 g + boric acid (H₃BO₃) 0.25 g + extra15 g KH₂PO₄ (2x of base form.) 8 Same as the base, except the ratio is1:2:1 of the MgO:MKP - (KH₂PO₄):stucco hemihydrate (CaSO₄•½H₂O)

For each of these samples, the resulting materials were analyzed forcontent, and homogeneity. Quantitatively, TABLE 3 below shows theresults, and these are similar in format to those of TABLE 1 above.

TABLE 3 KMgPO₄•6H₂O K₂Ca(SO₄)₂•H₂O Unreacted MgO CaSO₄•0.67H₂O Sample(Struvite-K) (Syngenite) (Periclase) (Bassanite) no. (wt. %) (wt. %)(wt. %) (wt. %) 1 23.1 46.6 29.1 1.2 2 20.0 49.2 29.9 1.0 3 18.7 48.831.5 1.0 4 19.4 47.4 32.2 1.0 5 23.0 47.4 28.6 .9 6 20.1 33.9 42.2 3.9 758.8 24.0 7.3 9.9 8 52.8 29.8 16.1 1.3

In addition to the above quantitative results, several observations weremade, including that the process yielded a formulation that was processfriendly and yielded a board with a stronger core. It was alsodetermined that changing the timing of the reactions by, for example,increasing mix time from one stage to two stages ranging from 45 to 90seconds yielded a stronger core material with water resistance withoutneed for wax or silicone. This is presumed to result form a higherStruvite-K yield. Finally, a close microscope examination of the setmaterials indicated that in many of the samples, crystallizationoccurred in a nonhomogenous way in the final materials. That is, wellformed crystallization occurred. The crystals, believed to be Struvite-Kcrystals, were determined to have formed in a boundary layer around thevoid spaces and between the voids and rest of the mixed product. Aphotomicrograph of one of these is shown in FIG. 1. As can be seen, thephotomicrograph shows crystallization of the boundary between the voidspace and the surrounding matrix. This is understood to comprise acrystalline Syngenite/Struvite-K structure, resulting in betterstructural rigidity in the resultant composition.

A second batch of lab test using a similar procedure was run as setforth above. The following TABLE 4 shows the sample constituents againusing a base mixture as follows: 15 g MgO, 15 g MKP (KH₂PO₄), 0.15 gH₂SO₄, 0.25 g boric acid (H₃BO₃), 0.05 g dispersant. One difference inthis base structure from the one in TABLE 2 above is that the amount ofstucco (hemihydrate CaSO₄.½H₂O) was varied, requiring an increase inwater as well.

TABLE 4 Sample Utilizing the above Base formulation the No. followingmaterials were added by weight 1A 15 g stucco, 20 g water 2A 20 gstucco, 24 g water 3A 25 g stucco, 28 g water 4A 30 g stucco, 32 g water5A 35 g stucco, 36 g water 6A 40 g stucco, 40 g water 7A 50 g stucco, 48g water 8A 60 g stucco, 56 g water 9A 15 g stucco, 27 g water, an extra15 g MKP

For each of these samples, the resulting materials were analyzed forcontent, and homogeneity. Quantitatively, TABLE 5 below shows theresults, and these are similar in format to those of TABLES 1 and 3,above.

TABLE 5 Unreacted KMgPO₄•6H₂O K₂Ca(SO₄)₂•H₂O MgO CaSO₄•0.67H₂OCaSO₄•0.5H₂O * CaSO₄•2H₂O Sample (Struvite-K) (Syngenite) (Periclase)(Bassanite) (Bassanite) (Gypsum) no. (wt. %) (wt. %) (wt. %) (wt. %)(wt. %) (wt. %) 1A 20.6 46.0 29.8 3.7 <0.1 <0.1 2A 14.0 45.1 27.6 <0.113.3 <0.1 3A x 56.6 26.9 <0.1 16.5 <0.1 4A x 57.4 21.5 <0.1 21.2 <0.1 5Ax 50.7 21.5 <0.1 27.8 <0.1 6A x 44.0 21.4 <0.1 34.6 <0.1 7A x 43.4 14.9<0.1 41.7 <0.1 8A <0.1 45.5 11.0 <0.1 43.5 <0.1 9A 66.2 27.0 6.8 x <0.1<0.1

Additional samples, deviating from the 1:1:1 ratio of the previousmixtures and not using the base composition of the first eight samples,were made up by use of the following formulations listed individually inTABLE 6 below:

TABLE 6 Sample MgO/MKP No. Constituent materials Ratio 11A 15 g MgO,50.65 g MKP, 33.52 g water   1:3.38 (stoichiometric struvite production)12A 15 g MgO, 7.5 MKP, 20 g stucco, 24 g water, + 2.0:1.0 0.15 g H₂SO₄ +0.25 g boric acid (H₃BO₃) + 0.05 g dispersant 13A 15 g MgO, 7.5 MKP, 30g stucco, 32 g water, + 2.0:1.0 0.15 g H₂SO₄ + 0.25 g boric acid(H₃BO₃) + 0.05 g dispersant 14A 15 g MgO, 7.5 MKP, 40 g stucco, 40 gwater, + 2.0:1.0 0.15 g H₂SO₄ + 0.25 g boric acid (H₃BO₃) + 0.05 gdispersant 15A 15 g MgO, 7.5 MKP, 50 g stucco, 48 g water, + 2.0:1.00.15 g H₂SO₄ + 0.25 g boric acid (H₃BO₃) + 0.05 g dispersant

For each of these samples, the resulting materials were analyzed forcontent, and homogeneity. Quantitatively, TABLE 7 below shows theresults, and these are similar in format to those of TABLES 1, 3, and 5above.

TABLE 7 Unreacted KMgPO₄•6H₂O K₂Ca(SO₄)2•H₂O MgO CaSO₄•0.67H₂OCaSO₄•0.5H₂O * CaSO₄•2H₂O Sample (Struvite-K) (Syngenite) (Periclase)(Bassanite) (Bassanite) (Gypsum) Mg(OH)₂ no. (wt. %) (wt. %) (wt. %)(wt. %) (wt. %) (wt. %) (Brucite) 11A No data available 12A <0.1 36.321.2 <0.1 19.9 <0.1 22.6 13A <0.1 33.2 10.8 <0.1 29.5 x 26.5 14A <0.127.0 4.3 <0.1 36.8 12.1 19.8 15A x 30.6 5.6 <0.1 <0.1 <0.1 25.9

As is evident in samples 12A-15A, a significant amount of the Magnesiumoxide (MgO) failed to take part in the main reaction and insteadgenerated a significant amount of a reaction by-product of a mineralidentified as Brucite, (Mg(OH)₂), which was not present in the othersamples. It is considered that an excess of MgO which was dissolved at ahigher temperature caused the precipitation of the Brucite by-product.

A third lab test of fifteen samples was conducted by continuously mixingraw materials at specified rate and time. This test run was specificallydirected to determine the effect of change in ratios of raw materials onthe properties of the product and which variables in production affectdifferent specified characteristics, such as product yields. Waterdemand was different for different regions in the diagram. As a visualaid, the solid constituents have been mapped in a ternary diagram 10(FIG. 2) and tabulated in TABLE 8 by weight percent. As can be seen froma comparison of the point plots of the different formulations in thephase diagram 10, some data points, e.g., L, M and N are high stuccoformulations, A-D are high MgO formulations, and the group comprisingH—N are high MKP (KH₂PO₄) formulations, while E, F and G are essentiallyequally weighted between MgO and MKP. As can be seen by the linearprogression of the connecting lines in the vertical directions, apattern was intended to maintain a constant ratio between MgO and MKPwhile varying only the stucco content. In the horizontally alignedpoints, the stucco content is maintained constant and the ratio betweenMgO and MKP is varied. The results obtained on the strength and presenceof Struvite-K are set forth in TABLE 8. Optimized strength performancefor acceptable cost was obtained for at least formulation J.

The characteristics tested for in the Sample J formulation were waterabsorption, shrinkage in a furnace muffle test (a direct indicator offire resistance) and mechanical strength. No additives, such as boricacid, Polysiloxane, Lignosulfonate, Sulfuric acid, etc. were added todecouple the effect of additives from raw materials. To isolate thevariable tested for, only the four essential constituents were utilizedincluding the group magnesium oxide (MgO), Mono-Potassium Phosphate-MKP(KH₂PO₄), stucco (CaSO₄.½H₂O) at specified process parameters. Thesamples had the formulations with the water comprising 31 weight % ofthe final mixture:

TABLE 8 Sample The formulations of the following solid materials Sameformulation including 31 weight ID only, by weight percent, and wateradded 30% percent of water A MgO 62.5, MKP (KH₂PO₄) 12.5, stucco 25.0,MgO 43.75, MKP (KH₂PO₄) 8.75, stucco 17.50, water water 30.0 B MgO57.67, MKP (KH₂PO₄) 28.33, stucco 15.0, MgO 39.67, MKP (KH₂PO₄) 19.83,stucco 10.5, water water 30.0 C MgO 50.0, MKP (KH₂PO₄) 25.0, stucco25.0, MgO 35.0, MKP (KH₂PO₄) 17.50, stucco 17.50, water water 30.0 D MgO43.33, MKP (KH₂PO₄) 21.67, stucco 35.0, MgO 30.33, MKP (KH₂PO₄) 15.17,stucco 24.50, water water 30.0 E MgO 42.50, MKP (KH₂PO₄) 42.50, stucco15.0, MgO 29.75, MKP (KH₂PO₄) 29.75, stucco 10.5, water water 30.0 F MgO37.5, MKP (KH₂PO₄) 37.5, stucco 25.0, MgO 26.25, MKP (KH₂PO₄) 26.25,stucco 17.50, water water 30.0 G MgO 32.5, MKP (KH₂PO₄) 32.5, stucco35.0, MgO 22.75, MKP (KH₂PO₄) 22.75, stucco 24.50, water water 30.0 HMgO 31.67, MKP (KH₂PO₄) 63.33, stucco 5.0, MgO 22.17, MKP (KH₂PO₄)44.33, stucco 3.50, water water 30.0 I MgO 28.33, MKP (KH₂PO₄) 56.67,stucco 15.0, MgO 19.83, MKP (KH₂PO₄) 39.67, stucco 10.5, water water30.0 J MgO 25.0, MKP (KH₂PO₄) 50.0, stucco 25.0, MgO 17.5, MKP (KH₂PO₄)35.0, stucco 17.5, water water 30.0 K MgO 21.67, MKP (KH₂PO₄) 43.33,stucco 35.0, MgO 15.17, MKP (KH₂PO₄) 30.33, stucco 24.5, water water30.0 L MgO 16.67, MKP (KH₂PO₄) 43.33, stucco 50.0, MgO 11.67, MKP(KH₂PO₄) 23.00, stucco 49.0, water water 30.0 M MgO 10.0 MKP (KH₂PO₄)33.33, stucco 70.0, MgO 7.0 MKP (KH₂PO₄) 14.33, stucco 70.0, water water30.0 N MgO 3.33, MKP (KH₂PO₄) 6.67, stucco 90.0, MgO 2.33, MKP (KH₂PO₄)4.67, stucco 63.0, water water 30.0 O MgO 12.5, MKP (KH₂PO₄) 62.5,stucco 25.0, MgO 8.75, MKP (KH₂PO₄) 43.75, stucco 17.5, water water 30.0

It should also be appreciated that the weight percent of water in SampleJ set forth above was nominally set a 31 weight percent, the percentageof water relative to the solid constituents can also be varied anywherefrom 15 to 40 weight percent, with 25-31 weight percent being nominallyused as a benchmark for having a sufficient amount of solvent toinitiate the reaction of the constituents.

It is also important to recognize that water temperature is a criticalfactor in the process. Specifically, the temperature of the water as itis added to the solid constituents is an important consideration as itaffects the rate of reactivity of the constituents. An increase in thetemperature of the water increases the time that must pass for theslurry to set. Standard water temperature is at room temperature, aboutbetween 20.0° C. and 25° C. Thus, it is important to monitor and controlthe reaction rates to maintain the integrity of the resulting product.Too high a temperature, that is, over 50° C., can lead to cracking ofthe surface during the hardening process as the slurry sets, although atrend has been found increased temperature coupled with reduction ofliquid solvent may be desirable.

From the testing regime, the following clear trends for characteristicshave been determined: The inventive magnesium phosphate(Struvite-K/Syngenite) compositions exhibited significantly improvedcompression strength, water absorption and fire resistance compared to asimple Gypsum composition. Moreover, it has been determined that theproduct characteristics are indeed tunable with variables in the processparameters and raw material ratios and properties thereof. For example,those samples processed at a higher temperature with lower water contentexhibited higher compressive strength. Samples with higher shearrate/time exhibited higher compressive strength and marginal decrease infire and water resistance. Shear rate and time is the vigor with whichthe mixture is mixed in a mixer, the amount of time the mixing processproceeds and whether the mixing was done by hand or mechanically.

Samples with MgO calcined at higher temperatures exhibited higherstrength, samples with coarser MgO exhibited lower strength. Thisappears to exhibit an opposite behavior to that of water absorption andfire shrinkage properties. The one sample discussed above, Sample J, hasbeen found to have the most efficacious and optimal properties in theresulting formulation, such as compression strength, which result hasbeen attributed to the high Struvite-K content.

Referring now to FIGS. 3 and 4, an in-line and continuous process formanufacture of board panels is proposed. A plug flow mixer 20 is shownin FIG. 3, having an inlet aperture 22 and an outlet aperture 24. Whilea plug flow is shown as an example, other types of mixers, for example,a step reaction mixer, can be used to effectuate this process, as willbe recognized by those having skill in board manufacturing processes.Shown by the arrow at the inlet aperture 22, is the point at which thestarting constituent materials are input into the mixer 20 the processoccurring continuously in plug flow mixer 20 provides for even mixingthereof.

In addition to mixing the constituents, plug flow mixer 20 provides forthe reactions in the mixer as the constituents reach different stages inthe mixer 20. The constituent materials, are set forth in variousembodiments above, are input into the inlet from two streams of inputconstituents, as shown in FIG. 4. A liquid constituent stream 30, on theleft side of the schematic view of FIG. 4, shows the input of liquidconstituents, including required constituents, such as water, andoptional but preferred ones such as wax, polysiloxane, Acid/Base (asneeded), a dispersant and a retarder. From the stream 32 shown on theright side of FIG. 4, the required constituents comprise theconstituents MgO, MKP (KH₂PO₄) and stucco (hemihydrate), which are inputthrough the screw conveyor 32 driven by a motor 52 and crank 50.Optional and preferred constituents include filler/ball mill additive asan accelerator, Boric acid, and fiber. Stream 30 feeds the constituentmaterials by piping 34 or other appropriate means, and the solidconstituent stream 32 may be fed by a conveyor 32 by the motor 52/crank50 or other appropriate means. Both of these streams provide inputconstituents to the mixer 20 which includes one or more mixer devices38A, 38B, 38C, shown schematically in FIG. 4.

Referring again to FIG. 3, the mixer 20 is shown in more detail with thedifferent mixer devices 38A, 38B and 38C shown in the staged mixingprocess of the step reaction mixer 20. As is shown, there are variouslevels of the mixing constituents that are occurring as the constituentmaterials are mixed in stages to create the optimal conditions for thedifferent reactions which are occurring at different points (verticallyas shown in FIG. 3) and at different times with respect to the processstep as to which part of the reaction is occurring. That is, the timethat the constituent materials take to be mixed, react and flow from thetop material inlet 22 to the outlet 24 is a set time governed by theprocess parameters and mixing steps. These are conducted to take intoaccount the process and mixing times as the materials descend throughthe stack in the reactor mixer 20 due to the force of gravity. Aslabeled along the longitudinal (vertical) direction of the mixer 20, thetimes that have elapsed of the constituent/reaction products in themixer 20 are correlated with the depth level within the reactor chamber23.

As is shown in FIG. 3, the materials as these are deposited into thereactor chamber 23 of mixer 20, are continually mixed by the mixerdevices 38A, 38 B and 38C at the appropriate times duding the reactionprocess to obtain the desired products and any by products. As thesecond part of the reaction, that of the Struvite-K subreaction, isexothermic, the unset mixture of Syngenite, Struvite-K and gypsum,designated as a stream of product or reactant mixture 42, flows out ofthe outlet 24 at an elevated temperature onto the conveyor 40, moving inthe direction of the arrow. It is further processed in accordance withknown board panel processes. For example, an optional mat 44 ofreinforcing randomly aligned glass fibers can be unrolled and paid outfrom a roll 46 of the material of mat 44 and laid over the product orreactant mixture 42, as it is being transported by the conveyor belt 40in the direction of the horizontal arrow.

While a plug flow mixer 20 is shown in FIGS. 3 and 4, other types ofmixers and delivery vehicles are contemplated by this invention. Forexample, a single phase constantly stirred tank reactor may be providedfor continuous manufacturing of a stream of the inventive material.Inputting all of the reactant constituents together in a single vesselof the appropriate size, and allowing the mixing process to proceed fora total predetermined reaction time depending on the reactant productsdesired. The reactant constituents would be continuously mixed and theresidence time of the reactant constituents would vary at the point thatthe product stream is withdrawn from the single mixing chamber.

As well, other configurations are contemplated, depending on the finaldesired product. A constantly stirred tank reactor (CSTR) providing theconstituents a residence time approximating half of the total time forthe total reaction would be followed by a true plug flow reactor, suchas mixer reactor 20, having piping of appropriate length and diameterwith interspersed static mixers to provide the remaining reaction timerequired prior to placing on a manufacturing belt. As the belt moves thereaction products along the manufacturing line, the reaction would moreclosely approach completion to allow the product to be roughly cut intoappropriate lengths for further handling, and may include a set time fordrying and final cutting to length so as to provide a finished boardpanel product. This process and mixing regime would produce a boardproduct at the end of the manufacturing process that ideally should havean appropriate amount of free water therein contained to allow allreactants fully to reach the final composition.

Another option is for a series of three or more CSTR reactors linked inseries so that the reaction will be at more advanced stages in eachreactor as the flow progresses through the series. The product from theseries of reactors would be delivered to a manufacturing belt where thereaction would more closely approach completion to allow the product tobe roughly cut into appropriate lengths for further handling, includingany drying required and final cutting to length of the finished product.

A sample board production in an inline production was run on an actualboard manufacturing forming line, in which the lab runs were scaled upby about 100 times to test if the process is feasible for use in boardpanel production utilizing the inventive material combinations.Essentially the same formulations, that is, a 1:2:1 ratio, wereutilized, as discussed below. All the amounts were scaled up, and a muchlarger mixer and reactor vessel or chamber 23 was required. Theprocedure was also modified in significant ways to enable thecontinuous, rather than batch, production of the inventive materialcompositions for use in a board line running at almost normal speed ofrunning or a round 40 feet per minute of conveyor belt 40 in accordancewith the description of the embodiments referenced to FIGS. 3 and 4above.

Certain additional equipment was required for this production run notneeded in the lab runs as shown in FIG. 5. This equipment includes atank reactor 21, a mixer 20, one or more pumps 18, a roller coater 19,two may be preferred, one for each of the two surface layers. A coregypsum mixer and pump for providing a continuous flow of the coregypsum, that is, the lightweight core gypsum, that will make up thecentral layer that will ultimately comprise the central or core layerhaving little if any of the Struvite-K and Syngenite reaction productsis also provided but not shown in FIGS. 3 and 4. Thus, the final desiredproduct is to be a surface layer coated with the inventive materialcompositions “wrapped around” a lightweight gypsum core, as will bediscussed with respect to the board embodiments of FIGS. 6-11 below.

Referring now to FIGS. 3-5, the procedure to manufacture the surfacelayer coatings is essentially the same as those described above, exceptadjustments are required to be made for the vastly increased scale ofthe constituent materials. The following step-by-step procedure isexpected to produce the necessary coating layers.

Pre-mix the solid mixture, comprising a 1:2:1 ratio, that is,MgO:MKP—(KH₂PO₄):stucco (hemihydrate CaSO₄.½H₂O) the pre-mix phase tolast from between 30 to 60 seconds. To ensure that enough of the slurrymixture is made, about 15 kg of each of the base constituents isprovided. Proportional amounts of siloxane, a defoamer, and adispersant, such as polynapthalene sulfonate, may be added to thismixture and water in about the same weight proportion, or about 17 kg,is added to the dry constituents.

Mix the resulting slurry for between 30 to 60 seconds in the largecontinuous mixer 20. After 15 seconds of mixing, the mixture started tosolidify. It has been found that continued mixing will re-liquify themixture. This is Phase I mixing. Upon finishing with this initial PhaseI mixing time, a timing sequence was commenced. Each minute after thisinitial Phase I mixing time, the mixture was again mixed vigorously for5 second periods separated by 55 second intervals. This is the Phase IImixing.

The formulation used in the production run causes the product to set-upanywhere from 5-20 minutes after the water is added to the powdermixtures. Due to the type of mixer used, however, the mixing occurredunevenly and no product was obtained out of the mixer/reactor in anyappreciable amounts for technical reasons.

Referring now to FIGS. 6-11, the board panel products in differentconfigurations are shown as separate board panel embodiments. Boardpanels may comprise multiple facer materials, preferably one or two, butthe invention contemplates even no facer materials. Such facer materialsmay be of paper, fiberglass, thermoplastic or other materials in aclosed or open mesh or weave, or any other appropriate configuration.When a random glass mat is used as the carrier for both the top andbottom faces of the resultant board panel, the reacted slurry isdeposited upon these carriers at a forming station, and then provided toa shaping device, such as an extruder or rollers, that determine thefinal board thickness.

In FIG. 6, the composite Syngenite-Struvite-K material board 110 isshown in cross-section having a central gypsum core 111. All surfacelayers including the top 114, bottom 116 and side 118 surfaces of thepanel 110 have Syngenite-Struvite-K-gypsum material coming directly fromthe reactor mixer 20 (FIG. 3) overlaying the gypsum core. The compositeSyngenite-Struvite-K material is that directly ejected from the outlet22 reactor mixer 20 (FIG. 3). It is also possible to embed a mat ofreinforcing glass fibers 112 within the top 114, bottom 116 and side 118surfaces of the panel 110.

In FIG. 7, a Syngenite-Struvite-K material board 120 is shown incross-section having a central core of lightweight core gypsum 121having foamed or aerated bubbles 123 that are injected into the corelayer 121, in accordance with known methods. All surface layers the top124, bottom 126 and side 128 surfaces of the panel 120 haveSyngenite-Struvite-K-gypsum material coming directly from the reactormixer 20 (FIG. 3) overlaying the overlaying the gypsum core. A mat ofreinforcing glass fibers 122 may be embedded within the surface layersof the top 124, bottom 126 and side 128 surfaces of the panel 120.

In FIG. 8, a Syngenite-Struvite-K material board 130 is shown incross-section having a central core of lightweight compositeSyngenite-Struvite-K material 131 having foamed or aerated bubbles 133that are injected into the core Syngenite-Struvite-K layer 125, inaccordance with known methods. All surface layers the top 124, bottom126 and side 128 surfaces of the panel 120 have a dense, that is,unaerated or unfoamed, Syngenite-StruviteK-gypsum material comingdirectly from the reactor mixer 20 (FIG. 3) overlays top 134, bottom 136and side 138 surfaces of the lightweight composite Syngenite-Struvite-Kmaterial comprising the core 131. A mat of reinforcing glass fibers 132may be embedded within the surface layers of the top 134, bottom 136 andside 138 surfaces of the panel 130.

In FIG. 9, a Syngenite-Struvite-K material board 140 is shown incross-section having a central core 142 of the compositeSyngenite-Struvite-K-gypsum material coming directly from the reactormixer 20 (FIG. 3), without any other reinforcing elements, as in theother embodiments described above.

In FIG. 10, a Syngenite-Struvite-K material board 150 is shown incross-section having a central core 152 of the compositeSyngenite-Struvite-K-gypsum material and having been foamed or aeratedin accordance with known procedures, to include air or foam bubbles 143within the core 141. No other reinforcing elements as in the otherembodiments described above are provided for in this embodiment of Board150.

In FIG. 11, a Syngenite-Struvite-K material board 160 is shown incross-section having a central core 161 comprising compositeSyngenite-Struvite-K material coming directly from the reactor mixer 20(FIG. 3). All surface layers, i.e., top 164, bottom 166 and side 168surfaces of the panel 120 have a dense, that is, unaerated or unfoamed,layer over the core 161. A mat of reinforcing glass fibers 162 may beembedded within the surface layers of top 164, bottom 166 and side 168surfaces of panel 160.

The invention herein has been described and illustrated with referenceto the embodiments of FIGS. 1-11, but it should be understood that thefeatures and operation of the invention as described are susceptible tomodification or alteration without departing significantly from thespirit of the invention. For example, the variations in startingmaterials of the various elements, or the specified reaction conditionsmay be altered to fit specific applications and desired yields. Also,additional variations may be introduced to provide differences in theresulting materials. For example, alternative additives to the startingconstituents may include, in combination and or permutations of thelisting herein, Boric acid, Polysiloxane defoamer, Lignosulfonate,Sulfuric acid, deionized water, tap water, and others as these becomerelevant to affect the reactions.

Although the additives described above are provided as activeconstituents for assisting, buffering or otherwise inducing one or moreof the reactions or subreactions to proceed, it is contemplated that theinventive composition and process may include other types of additivesand fillers, such as limestone, sand, fibers in proportions of frombetween 1 to 3 weight percent of the total board weight. These mayinclude short strand glass fibers (10-50 mm long and 10-80 μm in width),synthetic polymer fibers, paper, and agglomerations thereof, such aspaper and wood. Other additives may include starches, such as migratory,native, acid thinned, cationic starch, ethylated starch or dextrin, orpolymers, such as polyvinyl acetate, poly vinyl acetate-ethyleneco-polymer, polyvinyl pyrrolidone, crosslinked with polystyrenesulfonate, polyvinyl alcohol, methyl cellulose, hydroxyethyl methylcellulose, styrene-butadiene copolymer latex, acrylic ester latex,acrylic copolymer latex, polyester resin, epoxy resin, polymethylmethacrylate, or polyacrylic acid, all in the same proportional amountsof from between 1 to 3 weight percent of the total board weight.

In addition, the mixing process and speed may be varied to obtain moreoptimal desired results. Other variables that may be utilized tooptimize results are used natural instead of Synthetic stucco, the orderand timing of additions and ingredients may be varied, and with theintroduction of productions runs, mechanical mixing of the constituentsin for example, step reactors. Other variables that may have an effecton resulting ratios and products may include varying the sate as well asthe ratio of the raw constituent materials. These may include varyingthe addition rate, temperatures of the constituents, timing ofadditions, particle size, mix time, and other factors that may bedetermined as experience is gained with the reaction processes.

Accordingly, the specific embodiments illustrated and described hereinare for illustrative purposes only and the invention is not to beconsidered as being limited except by the following claims and theirequivalents.

What is claimed is:
 1. A process for the continuous manufacture of acomposition for use in a building product comprising: a) providing amixer reaction chamber; b) continuously feeding predeterminedconstituent materials into the mixer reaction chamber; c) continuouslymixing the predetermined constituent materials within said mixingreaction chamber to produce a slurry; d) withdrawing the slurry from themixer reaction chamber; and e) utilizing said slurry in the manufactureof a building product; wherein said predetermined solid constituentmaterials comprise the following in specified ranges by weight percent:MgO 3.33 to 70.00% KH₂PO₄: 4.67 to 70.00% stucco hemihydrate CaSO₄.½H₂O:10.5 to 90.0% and addition of water: 15 to 60% of the constituent solidmaterials.
 2. The process for the continuous manufacture of acomposition according to claim 1 wherein the specified ranges of saidpredetermined solid constituent materials further comprise: MgO: 10.0 to40.0% KH₂PO₄: 40.0 to 70.00% stucco hemihydrate CaSO₄.½H₂O: 25.0 to75.0% and including an amount of 15 to 60% by weight of liquidconstituent products relative to the solid constituents.
 3. The processfor the continuous manufacture of a composition according to claim 1wherein the specified ranges of said predetermined solid constituentmaterials further comprise a ratio of the MgO to the KH₂PO₄ between1:1.0 and 1:3.37.
 4. The process for the continuous manufacture of acomposition according to claim 3 wherein the specified ranges of saidpredetermined solid constituent materials further comprise a ratio ofMgO to KH₂PO₄ between 1:1.8 and 1:2.2.
 5. The process for the continuousmanufacture of a composition according to claims 1 through 4, whereinthe predetermined constituent materials further comprises a rateretarding compound, the compound chosen from one or more of the group ofcompounds consisting of boric acid (H₃BO₃) and sulfuric acid (H₂SO₄). 6.The process for the continuous manufacture of a composition according toclaim 5 wherein the predetermined constituent materials furthercomprises a defoamer, a dispersant and a silicone oil taken from thegroup consisting of polysiloxane (C₂H₆OSi)_(n), polydimethylsiloxane(CH₃[Si(CH₃)₂O]_(n)Si(CH₃)₃), polydimethylsiloxane and poly(methylhydrogen) siloxane and wherein the dispersant further comprisespolynapthalene sulfonate.
 7. The process according to claim 1 whereinthe constituent materials are reacted within the reaction mixeraccording to the following mechanism: MgO+KH₂PO₄+CaSO₄.½H₂O to producein varying predetermined amounts the reactant products: KMgPO₄.6H₂O andK₂Ca(SO₄)₂.H₂O.
 8. The process according to claim 1 wherein theconstituent materials are reacted within the reaction mixer according tothe following equation:3MgO+3KH₂PO₄+2CaSO₄.½H₂O+3H₂O→KMgPO₄.6H₂O+K₂Ca(SO₄)₂.H₂O+Ca⁺²+2Mg⁺²+2(PO₄)⁻³wherein the reaction occurs in the presence of one or more of thecompounds selected from a group consisting of sulfuric acid, boric acid,siloxanes and naphthalene sulfonate.
 9. A building board panel for usein constructing a building utilizing a building at least a compositionproduced from the process of one of claims 1 through 8, and wherein saidcomposition is disposed adjacent at least one of the faces of the boardpanel.
 10. A building composition for use in a building productcomprising Struvite-K (KMgPO₄.6H₂O), Syngenite (K₂Ca(SO₄)₂.H₂O) and oneor more of anhydrite gypsum, stucco (CaSO₄.½H₂O) and hydrated gypsum(CaSO₄.2H₂O), wherein the composition is used for producing a buildingmaterial having light weight, strength and integrity.
 11. The buildingcomposition for use in a building product according to claim 10, whereinthe resultant reaction products are in the following ranges:KMgPO₄.6H₂O: of from 0.1 to 67.0 weight percent; K₂Ca(SO₄)₂.H₂O: of from2.5 to 60.0 weight percent; and amorphous phase products and unreactedraw materials making up the remaining product.
 12. The buildingcomposition for use in a building product according to claim 11, whereinthe resultant reaction products are in the following ranges:KMgPO₄.6H₂O: of from 15.1 to 37.0 weight percent; and K₂Ca(SO₄)₂.H₂O: offrom 12.5 to 46.0 weight percent; and amorphous phase products andunreacted raw constituents making up the remaining product.
 13. Abuilding board panel for use in constructing a wall in a buildingwherein at least one of the compositions recited in claims 10 through 12is disposed adjacent at least one of the faces of the board panel.
 14. Abuilding board panel for use in building construction in which at leastone of the faces comprises a composition comprising Struvite-K(KMgPO₄.6H₂O), Syngenite (K₂Ca(SO₄)₂.H₂O) and gypsum.
 15. The boardpanel for use in building construction according to one of claims 13 and14, wherein the amount of Struvite-K (KMgPO₄.6H₂O) and Syngenite(K₂Ca(SO₄)₂.H₂O) comprising the face material exceeds 10 weight percent.